niubbi allle prime armi: problema con PHP_SELF

[piero.mac]

<?php
$passwd = "abc";

$password = $_POST['password'];

if(isset($password) and $password == $passwd):
{
  echo "ok sei connesso";
  exit;
 }
   elseif(isset($password) and $password != $passwd):
   {
   $password = NULL;
   echo "password errata, [url=". $_SERVER['PHP_SELF'] . "]Rifare la Login[/url].";
   exit;
   }
   else:
        {
        echo "<form action='". $_SERVER['PHP_SELF'] . "' method = 'post'>";
        echo "<input type = 'text' name = 'password'>";
        echo "<input type='submit'>";
        echo "</form>";
        }
endif;

?>